Electric control apparatus



0a. 20, 1942. H. ELLIOTT 2,299,082

ELECTRIC CONTROL APPARATUS Filed Dec. 3, 1940 8 Sheets-Sheet 1 iii "ZIIIIIIIII Oct. 20, 1942 ELLIOTT 2,299,082

ELECTRIC CONTROL APPARATUS Filed Dec. 3, 1940 8 Sheets-Sheet 3 rnr Oct. 20, 1942. H. F. ELLIOTT ELECTRIC C ONTROL APPARATUS Filed Dec. 3, 1940 8 Sheets-Sheet 4 flat 20, 1942. H. F. ELLIOTT 2,299,082

ELECTRIC CONTROL APPARATUS Filed Dec. 3, 1940 8 Sheets-Sheet 5 17; 15%? 155 [f6 15? /64 1/2? x 174 a;

1 166 14315; f z W Z Oct. 20, 1942. H. F. ELLIOTT ELECTRIC CONTROL APPARATUS 8 Sheets-Sheet 6 Filed Dec. 3, 1940 WNW WW haw NQ Z Z W Oct. 20, 1942.

H. ELLIOTT ELECTRIC CONTROL APPARATUS Filed Dec. 3, 1940 8 Sheets-Sheet '7 mm \mm. gm wmm Oct. 20, 1942. F. ELLlQTT 2,299,082

-ELECTRIC CONTROL APPARATUS Filed Dec:' 3, 1940 8 Sheets-Sheet 8 Patented Oct. 20, 1942 UNITED STATES PATENT OFFICE 2,299,082 ELECTFIC CONTROL APPARATUS Harold F. Elliott, Palo Alto, Calif.

Application December 3, 1940, Serial No. 368,334

22 Claims.

My invention relates in general to control apparatus and more in particular to electric control apparatus employed in tuning a radio receiver to a plurality of predetermined signal frequencies. This application is a continuation in part of my application Serial No. 277,856 filed June 7, 1939.

A tremendous amount of development work has been carried on for a number of years on electric tuners for radio receivers, and many different structures have been utilized commercially. Although several of these devices have accomplished the actual tuning of a radio receiver in a fairly satisfactory manner, the electric tuners in commercial form have substantially all been complicated and expensive and so large that they took up a considerable amount of space in the radio receiver apparatus to which they were applied. The complicated structure increased the cost of the tuners and in many instances the servicing and maintenance thereon; to such an extent that the complete radio receiver' to which the tuner was adapted was out of the popular price classes, and sales thereof were relatively limited. Furthermore, the bulkiness of the tuners of the prior art was such in many instances that it could not be employed in many of the popular priced receivers enjoying large sales because such receivers were relatively small in size as a result of the popular demand as well as the price thereof. In addition, the prior tuners operated relatively slowly, in fact so slowly that they normally required holding circuits operable during the tuning operation, which increased the complexity and cost of the devices. The slow operation was not attractive to the operator.

It is an object of my invention to provide improved electrically operated control apparatus which can be readily applied to many types of controllable mechanism including automobile radio receivers, and radio receivers for home use.

A further object of my invention is to provide a compact, simple, rugged, and inexpensive electrically operated control apparatus.

. A still further object is to provide electric control apparatus which operates very quickly and positively, and which can be quickly and simply adjusted to various predetermined control positions without the use of special tools or the like.

One of the features of my invention is the provision of the control apparatus in a preassembled unit which can be completely assembled and testassembled into the structure for which it is adapted.

Another feature of my invention is the provisionof a rotary control unit having magneti ally operated pivoted latches acting with control rings in the complete control operation, in which the latches, control rings and armatures for the magnets are of one size and formed of metal stampings whereby to reduce manufacturing costs of the unit to a minimum.

Yet another feature of my invention is the provision of a rotary control unit having magnetically operated pivoted latches acting with control rings in the complete control operation, in which the latches and associated magnet structures are angularly spaced about the control unit whereby to provide for a standardization and consequent reduction in the cost of the magnet structures.-

A still further feature of my invention is the provision of a tuning unit having a reversible driving motor in which a relay switch operates to close the motor energizing circuit and to mute the receiver during a tuning operation and to shut off the motor and to open the receiver on completion of the tuning operation. 7

Yet another feature of my invention is the provision of a tuning unit which includes frequency changing means adapted for operation by a unied under operating conditions before it is ever 53 directional rotating control shaft, in which the frequency changing means is rotated from a closed position to an open starting position by about a quarter revolution of the control shaft. The control shaft is in operative association with a switch which functions to turn the receiver off during this period of condenser rotation. This provides a simple and inexpensive means for automatically turning the set oil! and on during a tuning operation and saves the cost of a power relay.

The compactness of the complete tuner of my invention and particularly that of the control ring assembly is an important feature of my invention. The illustrations in Figs. 1 to 3 are made full size as to a commercial embodiment of the invention, and a second commercial embodiment is illustrated in Figs. 11 to 13 in actual size.

A still further feature of my invention is the I Fig. 1 is a top plan view'of my complete con- 7 trol device in a preassembled unit;

Fig. 2 is a front elevation thereof; Fig. 3. is a vertical sectional view approximately along the line H of Fig. 2;

Fig. 4 is a detail elevational view of a separator disc for limiting the axial movement of a control ring, and one of the elements for varying the friction on such disc and ring, taken along the line 4-4 of Fig. 3;

Fig. 5 is a detailed, somewhat diagrammatic illustration of a control ring, a pivoted latch, and the switch and solenoid structure associated therewith. In this figure the latch is shown on the high side of the control ring with the operating switch in a corresponding position, as contrasted to the idle position for this structure in Fig. 6 is a view similar to Fig. 5, showing the same structure in operating position, with a latch on the low side of the control ring;

Fig. '7 illustrates the same structure with the latch and control ring instopped position, which is the same regardless of whether the control ring rotates in a direction corresponding to the high side or the low side thereof;

Fig. 8 is a detailed sectional view approximately along the line 8-4 of Fig. 2, showing the adjusting screws and associated switch elements adjusted by such screws;

Fig. 9 is an elevational view of the preassembled unit looking to the left in Fig. l, with the control ring assembly and the rotor and and stator plates of thevariable condenser omitted for purposes of clarity in illustration;

Fig. 9a is an enlarged detail view of the slip clutch for the device of Figs. 1 to 10;

Fig. 10 is a. schematic illustration of a circuit for one adaptation of my invention as embodied in Figs. 1 to 9, inclusive;

Fig. 11 is a front elevation of a modification of my invention;

Fig. 12 is a top plan view of the complete preassembled unit of Fig. 11;

Fig. 13 is a fragmentary sectional view approximately along the line l3-i3 of Fig. 11;

Fig. 14 is an illustration similar to that of Fig. 5, showing the control ring of the modification with a pivoted latch in the high side of the rin and contrasted tothe idle position for the latch and switch in Fig. 11;

Fig. 15 is an illustration similar to Fig. 14, with the pivoted latch on the low side of a control in Fig. 16 illustrates the pivoted latch in stopped position on the control ring and the switch structure in a corresponding position;

Fig. 17 is a schematic illustration of a circuit diagram for one adaptation of a modified structure of Figs. 11 to 16, inclusive;

' Fig-181 illustrates the tuning unit of Fig. 2 with a switch mechanism adapted for operation with alternating current;

Fig. 19 is a detailed, somewhat diagrammatic illustration of a control ring with the latch on the low side of the control ring and the solenoid structure in its closed position;

q Fig. 20 is a view similar to Fig. 19 showing the aaoacsa latch on the hi h side of the control ring with the solenoid structure associated therewith in an energized condition;

Fig. 21 illustrates the same structure in its rest position:

Fig. 22 is a fragmentary sectional view of a latch portion as seen along the line 22--22 in Fig. 18;

Fig. 23 is a fragmentary view of a latch portion as seen along the line 23-23 in Fig. 18;

Fig. 24 is a sectional view taken along the line 24-24 in Fig. 19;

Fig. 25 illustrates somewhat diagrammatically a control circuit for the tuner of Fig. 18 when operating with alternating current; and

Fig. 26 illustrates somewhat diagrammatically a control circuit for the tuner of Fig. 18 when operating with direct current.

In practicing my invention I provide a frame for a preassembled radio tuning control unit which includes resonant frequency changing structure such as a variable condenser mounted on the frame, and a rotary control assembly angularly adjustably supported on a rotary shaft journaled in the frame and operatively connected with the resonant frequency changing structure of the complete unit. Control rings in the control assembly are normally frictionally held against rotation relative to their supporting hub and rotary shaft, but the friction can be removed and the rings individually and independently rotated relative to the hub to a position corresponding to 'a predetermined signal frequency. With the control rings then frictionally retained against rotation, the control assembly and the resonant frequency changing structure therewith' are rotated by suitable driving means, such as an electric motor through the various predetermined tuning positions where each control ring, as it is selected for a tuning operation, is stopped mechanically by a pivoted latch riding on the circumference of the control ring. Each pivoted latch is selectively brought into engagement with a corresponding control ring upon pushing a control button or otherwise closing an operating switch and circuit to energize a solenoid therefor. The energizing circuit can be closed at the radio receiver or from a remote position. Rotation of the control ring assembly by the electric motor continues until the latch engages a recess in the selected control. which has been previously adjusted to correspond in position to a desired signal frequency. The button switch or some other operating switch is held closed during this entire tuning operation and when released at the stop position for the control ring, opens the driving motor circuit.

Referring now tothe drawings, a substantially U-shaped one-piece frame I ll supports a variable condenser II and a motor l2. These portions of the complete unit are supported on the body portion of the frame and a switch portion, indicated generally by the reference character I 3, is supported on a frame extension I4, andanother frame extension I 6 supports the operating solenoids for the pivoted latches, as will be hereinafter explained. A relatively heavy rod or bar I1 is fixedly supported in the two legs l8 of the frame I 0 with one end of the shaft extending beyond its adjacent frame leg id for pivotally supporting thereon all of the latches as IS. The adjustable and rotatable control assembly 2| is mounted on an extension of the condenser shaft 22, or a second shaft coupled thereto, and such control assembly'and the rotor'plates of the variablecondenser Ii are rotatably driven by the motor l2 through a train of gears including a fibre gear 22 on the motor shaft 24, an intermediate spur gear 28 and pinion gear 21 secured thereto, and a segmental gear on the back plate 20 of the control assembly on the rotary shaft 22. The spur gear 2! and pinion gear 21 are each rigidly secured to a shaft 20 rotatably supported in a pair of frame plates 3| mounted onto the end motor frame plate at each end of the motor. A solenoid." for the muting relay, as will be described. is mounted on a supplementary bracket 38 which likewise is secured onto one end of the motor frame.

All of the above described structure is preassembled as a complete unit and with it all open and readily available, as shown in Figs. 1, 2 and 9, particularly, it is completely checked and tested before it is assembled into the radio receiver for which it is adapted.

As to the rotary control assembly, this includes a die-cast one-piece member including a hub portion 34 rigidly secured to the shaft 22 by set screws or the like, and the integral combination back plate and segmental gear 28. Integral with the back plate 28 are three bosses ll equally angularly spaced around the back plate as shown in Fig. 4, each having a center cavity 21 therein. The bosses 36 are connected with the hub 34 by integral ribs 3| therebetween. The outside of each boss 38 is curved slightly to correspond to a circle drawn from the center of the shaft 22 as a center and passing through the outside surface of each boss, and supported upon the three bosses 30 are a plurality of identical control rings 38 (Figs. 3 and corresponding approximately in inside diameter to the diameter of the circle just described. Intermediate each two control rings 30 and on the outside of the control assembly at each end thereof are identical separators or friction discs 4| (Figs. 3 and 4). Each disc 4i is provided with a plurality of inner-webs 42, and the discs are secured to the die-cast member against angular movement with relation thereto by means of a screw 43 extending through a corresponding aperture in each web 42, and corresponding washers 44 (Fig. 3) therebetween. Each screw is threadably secured in a corresponding threaded aperture 44 in the back plate 28 of the die-cast member. The washers 44 correspond in thickness substantially to the width of the control rings 19, and space the discs 4| apart a corresponding distance. The discs, or separators, are provideddn a thin flexible fibre composition material. As can be seen from Fig. 4, the ringlike outer portion of each separator is spaced slightly from the three bosses It and flexes axially slightly at the outer circumference due to the radial distance between the fastening screws 43 and the circumference of the disc. Although these discs positively separate the control rings 39 they do permit a slight axial movement of the rings so as to permit the control ring assembly to open up enough to permit an angular adjustment of each control ring. with reference to the bosses II, and hence the rotary shaft 22 to which the die-cast member is rigidly secured. As previously described, the separators are all fixed with reference to the'die-cast member and prevent the angular movement of control rings adjacent a ring being angularly adjusted. Due to the thin- Q ness of the separators the entire control ring assembly is very narrow as can be seen in Figs. 1

' and 3 particularly to in turn assist in making the entire unit relatively narrow, and very compact.

In the operation of the control apparatus, and after the control rings 29 are each set to a predetermined angular position with reference to the shaft 22, as will be explained, the rings I! and the friction discs 4| are compressedaxially as an assembly and frictionally retained against movement relative to the die-cast member and hence the shaft 22. The necessary frictional pressure is obtained by a friction unit which includes a plurality of one-piece levers 48 secured adjacent one end to the control assembly by means of screws 49 threadably secured in the apertures 31 of thebosses 38. A shim ll of spring steel is employed intermediate the head of the screw 49 and the body of the lever 40 to provide some spring pressure upon the ring assembly to prevent the rings slipping out of adjustment during the operation of setting them for the desired tuning frequencies. The friction unit also includes an apertured cap-like member 52 having a plurality of radial arms 53 on the outside thereof bent at right angles to the body of the member for engaging in corresponding notches 54 extending axially on the outside of the hub 34. The aperture 56 in the member 52 is provided at an embossed portion thereof, and has an angular collar thereon. The collar is threaded to receive a screw 51, while the inner end of each of the levers 43 is notched slightly to conform to the circumference of the collar. The same end of each lever is beveled to fit with the adjacent levers as shown in Fig. 2 and form a broken aperture at their inner end conforming in shape and size to the circumference of such collar. The screw 51 threaded in the member 52 engages a hardened steel disc 34' pressed into a recess in hub 34, at the end of the rotary shaft 22. Rotatingthe screw 51 in a clockwise direction for a right hand thread causes the member 52 to move axially to the left as viewed in Fig. 3 relative to the screw 57, and as it moves it'carries therewith the inner end of each of the levers 48. With the levers 48 retained at the screws 49, their outer ends compress the rings 39 and discs 4| against the back plate 28 until the desired frictional pressure on the rings is obtained.

Each control ring 39 is preferably die-cast in metal, but inasmuch as its function is purely mechanical and not electrical it can be provided in any material desired. The ring includes a high side H and a low side L each extending over slightly less than of the outer surface of the ring, and separated at contiguous ends thereof by a recess R (Fig. 5). A stop shoulder 40 is provided on one side of the recess R at the high side H of the ring. Cooperating with each ring 38 is a corresponding latch l9 pivotally mounted on a fixed shaft I! as previously described. In the present embodiment of my invention, six latches are employed, as shown in Fig. 9. In order to provide as compact an assembly as possible, arid provide adequate mounting and. operating space for the' latch magnets as will be described, and yet maintain the tips of the latch arms 59 all in alignment, the six latches are pivoted on the same shaft H, but the magnet arm SI of each latch varies in length, and symmetrical latches are provided in pairs. For convenience the pair of latches having the shortest magnet arm ii are indicated by the reference character l9 (Fig. 9), those latches having the next longest magnet arm are identified by the reference character 19, and the third pair of latches are numbered l9". Armature portions 62, 62 and 62" on the latches IS, I! and I9" respectively, extend at right angles and outwardly therefrom a varying distance, and the actuating magnets 08, with one for each latch, can be mounted in two Milt lines on the frame extension I, as shown in I'lgs. 1 and 2, and still be directly in the path of movement of the armatures. The core I for each magnet is rigidly secured in a corresponding aper-' ture in the frame extension II by soldering the core to aplate I6 as shown at I". This arrangement permits accurate positioning of the magnets, latches, and rings relative to one another in an optimum operative relationship. The winding for each magnet is grounded to the frame for the control unit as is shown in Fig. by se-' spacing of the control rings 39 in the control assembly 2 I Fol-purposes of illustration a latch I9 is shown in Figs. 2, 5, 6, and I, with its associated control ring 39 and magnet 63. The latch is shown in its three possible operating positions with three corresponding positions of the ring 10, and the switch mechanism I3 is shown in three corresponding positions to which it is operated by the latch I9. This mechanism is shown in idle position in Fig. 2. This mechanism includes a metal stop plate 69 mounted at one end upon fibre laminations II which are part of a similar insulating stack for the entire switch mechanism through which it is secured to the extension II by screws I2. The other end of the stop plate is adjustable relative to an ear I3 on the latch I9 by means of an adjusting screw I4 secured in extension I4. The ear I3 of the latch I9 and the corresponding ears of the other latches rest against this stop plate 69 when in idle position. They are urged to this position by spring arms I6 secured to the frame extension l6 which bear against a corresponding radial ear Ii on the latch I0, and similar ears on each of the other latches. The ears I3 of the latches operate for electric switching purposes against an insulated switch arm I! secured to a metal switch leaf I9 which in turn is supported in the lamination stack II. The leaf I9 has a pair of contact points 8| extending to each side of the switch arm I8 for engagement either with a corresponding contact point on the metal switch leaf 82 or a switch leaf 03. The leaves 82 and 83 are likewise secured in the lamination stack and insulated from each other and from the metal portion of the switch mechanism thereby. The switch leaf 83 bears against an insulating plate 84 as shown in Figs. 2 and 8, particularly, with the latter being flexible enough to be movable toward and away from the switch arm I8.

Gap adjustments for the various flexible elements of the switch mechanism as described are made by screws 86 and 81,. each threadably secured in the frame extension II and bearing against or operatively connected with switch leaves 83 and 82 respectively. The adjusting screw 81 is insulated from the switch leaf 02 by a fibre button 88 secured to the switch leaf 02, while screw 86 is insulated from the leaf 8! by the insulating plat 84. The screws 06 and 01 aaoaoaa are insulated from the switch element through which they must pass in order to reach their corresponding elements and 82 respectively by being positioned in 1 enlarged apertures in the metal stop plate 09 and the metal leaf I0 on the switch arm I0 as shown clearly in Fig. 8. A wire spring I! is woven around the adjusting screws the magnet 32 and an armature 0| flexibly mounted in the stack of laminations as shown in Fig. 2. An insulating plate 92 is likewise mounted in the lamination stack for adjusting the position of armature 9 I The position of the insulating plate 02 and armature 9I is adjusted by a screw 93 threadably secured in the frame extension I4 and extending through corresponding apertures in the stop plate 69 and switch arm I8 was to be out of contact therewith as shown in Fig. 8. The position of the plate 92 determines the idle position of the armature 9| and consequently the armature gap at' the magnet. When the driving motor is energized the magnet 32 is energized to attract the armature SI and close the muting circuit as will be subsequently explained.

The operation of my electric tuner will be more clear from a consideration of the circuit diagram of Fig. 10. A series of push-buttons are provided with each one indicated by the reference character 95, and these may be appropriately mounted on the radio receiver itself or on a remote unit connected with the receiver by an electric cable. After the receiver is turned on by closing the switch 96 in the current supply line forthe tuner and the radio receiver, a selected button 95 may be pressed to eng ge a pair of switch contacts 91 and 98; Engaging these contacts closes a circuit from the current supply 90, which in this case is a battery because the circuit is illustrated for an auto radio receiver, through the switch 96 (which has been moved to closed position from the position illustrated in Fig. 10) through a lead IM and I02, to a conductor I03 connected to the switch contact 91 and to pilot lamp I95. The conductor I03 is common to all of the switch contacts corresponding to contact 81 on each of the buttons 95. Switch contact 91 and conductor I03 may be electricallyconnected to a corresponding latch magnet 63, which is connected to ground at one side, through conductor or leads I04 via the switch contacts 58. Closing this circuit energizes the magnet 63 which attracts the corresponding pivoted latch IS thereto, and the angular movement of the latch under the attraction of the magnet 63 depends upon the angular position of a corresponding control ring 38 at that particular time. As illustrated in Fig. 10, the latch IS stops on the high side H of the ring 39. It is then in a position corresponding to that shown in Fig. 5 with the switch arm I0 in turn remaining in contact with the switch leaf 0!. The switch arm I8 and contact 82 are in engagement even at idle position, as shown in Fig. 2. The gap at idle position between the tip of the latch arm 59, and the high side H of th ring 39, and the gap between the switching ear I3 of the latch andthe switch arm I8 is such that when the latch I9 is pivoted slightly to the high side H of the ring 39, the arm I8 and contact 02 remain in engagement. Thi switch adjustment is accomplished by means of the screw ll against the stop plate 33 and the screw 31 against the switch leaf 32.

A third switch contact I36 is provided for the push-button 33, and although this is insulated from the contacts 31 and 33, it is spaced only slightly therefrom and the normal operation of the push button 95 moves the same inwardly so that it engages not only with the contacts 3'! and 33 but also the contacts I33. When this occurs a circuit is completed through the field F or the motor I2, extending through the conductor I 01, conductor I33, switch arm I3, switch contact 32, and through the motor field F and armature A to ground. The conductor I3! is electrically common to all of the switch contacts I36 for the push buttons 35. Energizing the motor field F causes the motor to rotate, to in turn rotate the control assemblyv through th gear 23, and the shaft 22 having th condenser H thereon. The direction of rotation of the motor will behereinafter described.

In order to prevent any undesirable noises at the loud speaker I 33 during the rotation of the condenser through various signal frequencies as it moves to the particular predetermined frequency desired, the voice coil III of the speaker is shorted out by drawing the switch arm' III of the muting switch to the magnet 32, energized when the motor current is energized, which completes a circuit through the switch arm and grounded magnet core, and the voice coil to ground.

The push button 33 is held in closed position by the operator until the timing operation is completed. This is so rapid that the button is I held only momentarily even while the condenser II and the control assembly 2| are moving the limit of their angular movement or approximately 180. In fact, in one. commercial embodiment of the invention the maximum angular movement of the tuning mechanism can be accomplished in approximately one second. In the position of the illustration of Fig. 10, the control ring 33 is driven in a counter-clockwise direction by the motor I2 when the latch I3 is pivoted to the high side H. With control rings of such relatively great diameter as shown in Fig. 2, and yet the maximum tuning movement being accomplished in approximately one second (in one embodiment), the great speed of movement of a control ring past the selectedlatch can be understood. Normally th ring driven in a counterclockwise direction passes the latch tip 53' at the recess R, permitting the latch to be pivoted until the tip strikes the low side L, which in turn opens contacts 13-32 and closes contacts 'I333 of the switch I3 to reverse the motor and drive the ring 33 in a clockwise direction. The tip 33' engages the high side of the recess R when the ring is moving in this direction. With the magnet arm SI 01' the latch I3 spaced away from the core of the magnet 33, as shown in Fig. 5, the arm is pivoted an additional. amount when the tip of the latch arm 33 reaches the recess R, to

, the stop position as shown in Fig. 7. As can be seen from this description the rotor mechanism -is always stopped when going inthe same direction, thus minimizing any possible inaccuracies in stopping position due to lost motion in the mechanism. and assuring the maximum precision in tuning. The magnet 33 and the motor l2 remain energized so long as the button 33 is held in operating position. The tip 33' of the latch arm 33 mechanically and positively seats in the recess R due to the shape of the tip and the recess, and holds the control assembly 2| and condenser l I against rotation. The outer or right hand surface of the tip 33' as viewed in Fig. 7 is preferably accurately formed upon the circumference of a circle with a radius equal to the distance from the center of axis H to such surface.

A slip clutch, as shown in detail in Fig. 9a, between the driving gear 23 and the motor shaft 23 permits the latter to rotate while the gear 23' and its connecting train are stopped, thus cushioning the blow which occurs when the latch tip 33 engages with the shoulder 33 for the recess R (Fig. 7), to stop and position the mechanism at the desired frequency. This clutch comprises a spring washer III, and a flat washer 3' supported on the shaft 23, with the spring washer II3 urging the gear 23 against the collar 23' on the end of the shaft. The washer III! in turn bears against a shoulder on the shaft 24. When the button 33 is released by the operator it is suitably pressed by a spring out of engagement with the contacts 31, 33 and I36, to open the motor circuit first and then the various magnet circuits. The spring flnger Ii acting on the radial ear II of the latch I3 returns such latch to idle position as shown in Fig. 2. This return motion of the latch is aided by the spring tension of the switch leaves, I3 and 33.

The operating circuit for the controlunit when the latch I3 is drawn into the low side L of the control ring 33 (Fig. 6) is substantially identical with that Just described except that the switch arm I3 is moved into engagement with the switch contact 33. This closes the motor circuit through the field F in a reverse direction, causing the motor to rotate the control assembly in a clockwise direction until the'tip of the latch arm 53 engages in the recess R as shown in Fig. '7, and as described above.

Before the control unit is operated for tuning purposes as described above, all of the control rings 33, or at least a number corresponding to the number of stations it is desired to tune, are set in predetermined angular positions corresponding to the tuning positions of the condenser II for each of the desired stations. Assuming that the screw 31 and its associated mechanism, including the levers 43, are in a non-friction position, a selected button 331s pushed in to complete the switch connections through the contacts 31, 33 and I36, to in turn energize a corresponding magnet 63 and the motor l2. This causes the corresponding control ring 33 which is still held under a slight friction by spring 5| to rotate until the tip of the latch arm 33 drops into the recess R oi the ring. The operafor either releases the button 35 entirely and then pushes it in only enough to engage the contacts 31 and 33, or originally lets the button move out of engagement with contact I36, thus maintaining the magnet 33 circuit and breaking the motor circuit. With the latch arm 33 in the recess R, the gear 23 and the die-cast member, including the hub 33 integral therewith, are rotatedmanually by the operator byan ordinary manual tuning knob at the radio receiver, or at a remote control unit. The knob may be operatively connected by a flexible cable or the like with a molded coupling II3 (Fig. 9) secured to the shaft 23 to which the gears 23 and 21 are likewise secured.

tion corresponding to the signal frequency desired. This position can be ascertained by the usual dial scale for the radio receiver, which is not shown here, and by listening, or using an output meter. When this position of the condenser II is obtained the button 95 is released to open the magnet energizing circuit. Ihis same procedure can be followed for each of the control rings 39, and with each ring separated from'each other ring in the control assembly 2| by the axially yieldable but angularly fixed discs or separators 4|, there is no possibility of the relative movement between a control ring 39 and the shaft 22 causing any displacement of the control rings previously set.

The limits of movement of the rotors for the condenser II are of course determined in the condenser itself. Assisting in this limiting movement, however, is a rigid stop H4 on a plate H5 secured to the adjacent end of the frame for the condenser II which in turn is secured to the main frame In of the control unit. Shouleach limit of the condenser.

When the setting operation for the rings 39 is completed, the screw 511s rotated so as to move the cap member 52 threadablythereon in a direction axially of the shaft 22 and to the left as viewed in Fig. 3, and pivot all of the levers 48 to compress the rings and separator discs of the control assembly against the back plate 28 of the die-cast supporting member. Although a screw with an ordinary slotted head is illustrated in the various figures, to be turned by an ordinary screw driver, I may employ a suitable knob which can be turned by hand, such as that illustrated in Fig. -11. V The tuning unit shown in Figs. 18-26, is substantiaily similar to that illustrated in Figs. 1-10, except for the switch mechanism 13' and associated magnet structure 30! which are adapted for operation with alternating current. Similar numerals of reference, therefore, shall be used to designate similar parts. Figs. 1 to 17, inclusive, are taken directly from my application Serial No. 277,856, filed June 7, 1939. Since the tuner structure of Figs. 18 to 26 is similar in many respects to that of Figs. 1 to 10, it will now be described. It will be noted, therefore, thatthe refer e ace numerals relating to Figs. 18 to 26 donot chronologically follow those of Figs. 1 to 10.

With reference to Fig. 18, the'ring assembly 2| is similar in all respects to that described in connection with Fig. 2 and further explanation thereof is, therefore, believed to be unnecessary. Latches such as I30 and Nb are provided for the corresponding rings 33, the operation of each latch and its assembly relative to the switch mechanism i3 and corresponding control ring 33 being the same as that of the latches is hereinabove described in connection 2.

The armatures 62a and'62b are arranged for actuation by alternating current magnets 63a and 63b, respectively. Although only the two magnets 63a and 63b are shown, it is to be understood that there are as many magnets as there are latches. These magnets are oppositely arranged in two parallel rows, the magnets 63a and 63b being illustrated as the first magnets in such rows. Each magnet has its pole divided into two portions,one of which portions is fitted with shading rings, as indicated at 3, in a manner well known in the art. The magnets are mounted in ayoke member 302 of substantially U-shape having leg members 303 and 304. Finger portions 306a and 3061) on the latches I91: and l9b extend over the corresponding magnets 63a and 63b and are provided with extensible members 301a and 30112, respectively. Since the assembly and operation of each latch and its associated magnet structure is the same, only one latch, say l9a, will be referred to in the following description.

Connection between the extension 301a and armature 630. (Fig. 19), is made by a flat spring 308 of angulate shape having a body portion arranged substantially adjacent to and coextensive in length with armature 62a; An upwardly extending end portion 389 of the spring 308 is formed with an aperture 3l2, (Figs. 22 and 23) for receiving therein the extensible member 3010. A small auxiliary spring 3| 3 is attached to the side of the extension 301a at the aperture M2 and functions to eliminate any chatter, arising by virtue of alternating current operation, which might occur between the extension 301a and the spring 303 at the opening 3l2. A depending spring portion 3 is in abutting engagement with a supporting member 3 in a manner to keep the spring 308 under tension for a purpose to be later explained. The portion 3 and member 3 are secured to the leg member 303 by suitable screw means 3l6 or the like. Spring 308 is reinforced by additional laminated spring members 311 which in combination with the spring 308, serve to provide a spring tension on the armature 62a which is highly flexiblebut substantially constant over the complete operating range of the armature movement. Laminations 3" are secured as by a rivet or screw 3" to the upper side of the armature 62a, a pro- Jecting end portion 32| thereof extending ..,.through the member 3 whereby. to pivotal y support the armature 62a for pivotal movement into and from'its operating position with the magnet 6311.

Only two latches I30 and 13b are indicated, but

For purposes of illustration the latch i-Sa is shown in Figs. 18 through 21, with its associated control ring 33 and magnet 63a. The latch is shown in four possible operating positions with four corresponding positions of the ring 39, and 'the switch mechanism I3 is shown in four corresponding positions to which it is operated by the latch "a. The switch mechanism l3, which is common to all of the latches, is shown in its idle position in Fig. 21, includes a reversing switch for the motor I! which is substantially similar to the motor reversing switch hereinabove fully described in connection with Fig. 2.

'The metal stop plate 63, switch arm II and switch leaves 32 and 33 are all secured in the lamination stock II in a manner to be entire y insulated from each other. The free end of the stop plate $3 is adjustable relative to the latch ear 13 by means of the adjusting screw M which is secured in a frame extension member ll.

adjusted by the screw 33.

The ear 13' of the latch Ila and the corresponding ears of the other latches rest against the stop plate 93 when in idle position. It is urged to this position by the spring '393 in an obvious manner.

Gap adjustments for the various flexible elements of the switch mechanism l3 are made by screws 33 and 31 which are threadably secured in the frame extension l3, and are operatively connected withthe switch leaves 33 and 32, respectively. (Fig. 24). The screws 33 and 31 are insulated from the switch element 33 through which they must pass in order to reach their respective switch-leaves 33 and 32, by being positioned in enlarged apertures formed in the metal stop 33; the screw 33 being further extendedin a like manner through an aperture in During the tuning operation the radio receiver is muted so that undesirable noises which would normally be reproduced in the speaker for the receiver are eliminated. This muting is accomplished by a relay which is grouped with the reversing switch mechanism and includes a magnet 32 and a pivotally supported armature N of substantially hooked shape, it being understood. of course, that the relay is also common to all of the latches in the tuner structure.

The position of the armature 3| (Fig. 24) is adjusted by-a screw 33 which is threadably secured in the frame extension l3 and extends through corresponding apertures in the stop plate 33 and switch arm 13 so as to be out oi contact therewith. A supporting bracket 3" for holding the armature 3i in its open position is adiustably secured to a yoke member 322 for the magnet 32. The position of the supporting member 3 and hence of the armature 3| is Positioning of the plate 3" thus determines the open position of the armature 3| and consequently the armature gap at the magnet. When the driving motor I2 is energized the magnet 32 is energized to attract the armature 9i and open the muting circuit as will be subsequently explained.

The free or hook end of the armature 3l' has contacts 323 and 323 on opposite sides thereof which are selectively engageable with contacts 323 and'32l, respectively, the latter contacts being associated with switch leaves 323 and 323,

respectively. The switch arms 323 and 329 are suitably secured in the laminated structure II and are spaced from each other near their free ends by a spacing element 33 l which will be later explained.

The operation of the tuner structure of Fig. 18 is best understood from a consideration of the circuit diagram of Fig. 25. Alternating current is supplied to the circuit from a source 332 such as the usual 110 volt house current. In the event the tuner assembly is to be used in conjunction with a clock mechanism, a clock 333 may be arrangedacross the supply lines 333 and 333, as indicated, the master switch 331 being connected so as to shut off the energy supplied by 332 from everything but the clock. With a supply voltage of 110 volts, the power transformer 333 of the radio receiving set, in one commercial embodiment, is provided with a secondary winding 333 which is wound for about volts. The secondary winding 3 is wound for about 8 volts and serves to energize the heaters of the radio tubes and the tuning motor l2. A usual is closed of the magnet rent to the rectifier and tube 333 which energizes the B-supply circuit of the radio set.

A plurality of push button switches 333, one

' for each of the tuning magnets may be arranged at the radio receiver or remotely therefrom, the magnets being connected in parallel across leads 333 and 333. In series in the common return lead 333 oi the tuning magnets 63a-63f, is the winding of the relay switch magnet 32. winding 333 for the closing coil of a power relay which may be similar to that shown at MS in Fig. 17, is also connected in series in the common return 333. The opening coil for the power relay is indicated at 331. The power relay operates the switch 333 in the heater circuit and the switch 333 in the B circuit. Since the closing coil 333 of the relay is in the common return lead of all of the magnets "cl-63f, the power relay is closed whenever any magnet is energized. The opening coil 331 is in a circuit by itself and the relay is therefore opened only when the button marked OR is closed; the circuit including lead 333, conductor 3", lead 333 and secondary I coil 333. When the button marked "On is closed, the circuit comprised of lead 339, conductor 332. and lead 333 including only coil 336 and winding 333 is closed, a tuning magnet being energized only when a push button 333 is operated. A volume control motor 353 and suitable buttons 3 and 333 for raising and lowering the volume may be provided if desired, the motor being suitably connected across the leads- 333 and 333. 1

Let it be assumed that the tuning unit is in its idle position as indicated in Fig. 25 and more in detail in Fig. 21, the latch l9a being near the high side H of the ring 39. Contacts 323 and 321 of the relay switch are in contacting engagement so that the muting circuit shown at 351 and the radio set is ready for playing; the switch arm 13 being in contact with the switch leave 32 to complete the motor energizing circuit throughthe field 356 for one direction of rotation. Actuation of the push button 333 to energize the magnet 63a simultaneously energizesthe relay magnet 32 and the closing coil 333 for the switches 338 and 339. Energization '32 attracts the armature 9i to its closed position. This movement of the armature opens the. contacts 323 and 321 to open the muting circuit and also closes the contacts 323 and 323 to close the motor The flow of current through the motor field coil 333 eilects a rotation of the ring 39 in a counterclockwise direction as viewed in Figs. 18 to 21, inclusive. This arrangement of the switch mechanism l3, on energization of the magnets 32 and 33a, is illustrated in Fig. 20. It is to be noted that although the magnet 63a is energized the armature 32a is not pulled against the pole of the magnet 33a. Spring 338 and laminations 3i! are made with sufllcient initial tension to operate the switch I 3', as will be later: explained, which high voltage secondary winding 332 supplies cur- 7s tension prevents the armature 62a from closing against the magnet pole therewith. but this would require a larger and hence additional cost without accomplishing ny useful object. o

On rotation of the control 'ring 39a in a counter l2 through field 356.

when the latch H0. is on the high side H of the ring 39. There would be no objection in making the magnet strong enough to pull the armature into engagement;

asn ti.

.tion of the motor, the radio set continuing to be muted by virtue oi the closed contacts 323 and 326. With the latch arm 93a in engagement with the low side L oi the ring 33,. the armature 32a is pulled into engagement with the magnet 331;. This is accomplished byarranging the strength of the spring 333 and the laminations 391 so that the magnet 33a is not strong enough to pull the armature to its closed position when the latch is in engagement with the high portion of the control ring as previously mentioned in connection with Fig. 23. The spring strength, however, is such that the magnet is strong enough to pull the armature down wheh'the latch i3a engages the low side L of the ring as is shown in Fig. 19. It is to be understood, of course, that the magnet 33a may be of a size to draw the armature 32a to its closed position whenever .itis energized, but this would require a larger "magnet and the larger magnet is notfriecessary since the above described structure provides sufilcient force for emciently operating the switch mechanism l3. On reversal of the motor 12 by virtue of the movement of the switch arm 18 by the latch ear 13,.the rotation of the ring 33 is correspondingly reversed so that the latch tip 53a is positively moved into the notch R in a manner similar. to that previously fully explained in connection with the operation. of the tuning structure of Fig. 2. The function of pulling the latch 13a into notch R is accomplished by the action of the spring 338 and laminations 311. In this connection it is to tion, by virtue of the relative pivotal movements of the armature 3i, switch lea! 33 and latch ear be observed that a clearance gap indicated at '358 in Figs. 18-20, is maintained between the armature 62a and the spring 338 when a latch i312 is either on the low side L or in the gap R of a ring 39. It is desirable that this small gap be maintained in order to keep a spring pressure applied on the latch to maintain a frictional engagement between the control ring 33 and the latch when the latter is in thenotch R. I

On movement of the latch 83a to its operated position as indicated in Fig. 18, the latch ear 13 is permitted to move additionally in an upward direction to further raise the extension 18 on the leaf 13. This additional upward movement of the extension 18 moves the leaf 83 of the reversing switch into engagement with the insulating spacing member 331 previously noted, to lift the spacing member. Since the spacing member 338 'operatively connects the contacts 326 and 321, these contacts are moved relative to the armature 3| so that contacts 323 and 326 are opened and contacts 324 and 321 are closed. Opening of the contacts 323 and 326 opens the circuit of the motor 12' and the closing of the contacts 324 and 321 closes the muting circuit of the radio set so thatjthe set is ready for playing substantially concurrently with a stopping of the tuning motor. It is understood of course that the push button is held closed during the entire tuning operation. se of the push button 344 deenergizes the u jets 63a and 32 and the switch mechanism is re timed to itsidle position shown in Fig. 21. The contacts 324 and 321 continue to remain closed as the mechanism returns to its idle posii3. Since the spacer 33! is in engagement with the switch leaf 83 the relative positions of the contacts 323, 323, 326 and 3211 are thus maintained during the movement or the latch 03a from its operated position of Fig. 18 to its idle msition indicated inv Fig. 21. The set, therefore, is retained in a playing condition and the motor reversing switch is set to permit the current how in the motor circuit to pass through the held 353 on later actuation of a push button 333. The rotor mechanism 228 is thus always stopped when going in the same direction whereby to minimize any mssible inaccuracies in its stopping position clue to lost motion in the mechanism.

A slip clutch, as shown in detail in Fig. 9a, may be provided between the driving gear 23, and the motor shaft 23 to permit the latter to rotate while the gear 23 and its connecting train are stopped, thus cushioning the blow which occurs when the latch tip 33a engages with the shoulder 30 for the recess R (Fig. 18), to stop and position the mechanism at the desired frequency.

The predetermined angular positioning of the control rings 33 to correspond to the tuning position or the condenser H for each of the desired stations is similar in all respects to that fully described above in connection with Fig. 2.

From the above description or the tuner in Fig. 18 it will be evident that the switching mechanism 53' may be applied to the direct current tuner shown in Fig. 2 by simply substituting such mechanism for the corresponding. mechanism i3 shown in Fig. 2. As illustrated in Fig. 26 the circuit for this arrangement includes a relay switch operating magnet 32, an armature 3| and contacts 323, 324, 326 and 321 all as above described. The reversing switch, including switch arm 13 and switch leaves" and 83 is also the same as previously explained. In the idle position of the tuner the switch mechanism l3 is'arranged as shown in Fig. 26, namely with 344a for the magnet 83, the magnet 32 is energized, the circuit from the battery 33 including conductors 362, relay magnet 32, conductor 363, push button 344a and magnet 63, the circuit being completed through the ground connection 364. Energization of the relay operating magnet 32 attracts the armature 3|'- to close the contacts 323 and 326 whereby to energize the motor H, the motor circuit trom the battery 33 including conductors 362 and 366, switch leaves 13 and 82, motor field F, conductor 361, contacts 323 and 326 and grounded conductor 36L Closing of the contacts 323 and 326 occurs simultaneously with the opening of the contacts 324 and 321 so that the motor 12 is operated simultaneously with a muting of the radio receiver. The direction of rotation of the motor 12 is determined by the direction of current flow in the field F as controlled by the motor reversing switch in the manner above fully explained. In view of the above detailed description of the operation of the tuner of Fig. 18, a further explanation of the circuit diagram in Fig. 26 and its operation is believed to be unnecessary.

in Figs. 11 to 17, inclusive. The modification is assembly II8 by means of a train of gears including a pinion gear I22 secured to the motor shaft I23, and a segmental gear I24 fixedly secured to the control assembly II8, as will be described. Intermediate these gears is a gear I28 on a stub shaft I2I which carries the corresponding pinion gear I28 .in meshing engagement with the segmental gear I24. Intermediate the gear I28 and its shaft I2l is slip clutch mechanism comprising hub I and spring washer I25 which permits the motor to rotate when the control assembly is held. Hub I28 is secured to shaft I21 by a set screw, and gear I28, which is free to rotate relative to the shaft, is pressed against the hub I20 by spring washer I25, thus giving a friction drive between hub I28 and gear I28. Likewise supported upon the frame member FR. is a supplementary frame portion including a plate I28, a bracket I3I and another plate I32, all cooperating to support the pivoted latches, the magnets, and the switch mechanism operating therewith.

The control assembly II8 includes a die-cast one-piece support having a back portion I33 and a plurality of ribs I34 extending axially therefrom to a hub portion I38 in the center of the die-cast member. cavity at one side for fitting over the shaft I2I -as shown in Fig. 13, and a cavity at the other side for receiving friction adjusting mechanism as will be described. The outer edges of the ribs I34 support a plurality of control rings 38 thereon which are substantially identical with the control ring 38. These include a high side H, a low side L, and a stop recess R, as is clear in Fig. 14. Separating each two adjacent control rings 38' is a thin metal ring I38 which is likewise supported on the outer edge of the ribs I34. The rings 38 are angularly adjustable on the die-cast member as explained for the first embodiment of my invention, and the separator rings I38 are retained against angular movement by means of a pin I39 rigidly secured in the back plate I33 of the die-cast member and extending through apertures I40 (Fig. 11) in cars I40 integral with the rings I38. The pin I38 likewise extends through the gear I24 secured to the back portion I33 and serves as a guide pin for the two halves of' the gear I24 as shown in Fig. 13. This gear is provided in two axially aligned identical portions which are spread angulariy to take up back lash between the gear and driving pinion gear I28 in the well-known manner.

The control rings, when in set angular position, are held in such position by friction applying mechanism operating generally in the manner described with reference to the structure in the first embodiment of my invent on. The friction mechanism includes a screw I4I extending into the cavity in the hub portion I38 comprising a restricted portion I42 and an enlarged portion I43. The inner end of the screw I4I rests against a ball bearing in the restricted portion I42 and The hub portion includes a sembly as much as .an intermediate portion of the screw is threaded for threaded connection with a nut I44. The nut is hexagonally shaped, or in fact may be utilized in any shape other than round, and the side walls of the cavity I43 are similarly shaped so that the nut will not rotate in the cavity. It may however move axially therein. Levers 48 rest at one end against the circumference of the outer rings 39' and at the other and upon the outside face of the nut I44. The end resting upon the nut I44 is notched and beveled to surround the screw I as explained for the lever 48. Each lever is retained on the control assembly by a screw 43' extending into a corresponding threaded cavity in each rib portion I34 of the die-cast member. Upon rotating the knob I48 in a clockwise direction for a right-hand thread, for instance, the nut ,I44 thereon moves axially but non-rotatably to in turn move the inner end of each lever 48' to the left, as viewed in Fig. 13, to apply friction to the control assembly as has been described. In removing friction the knob I48 is rotated in the opposite direction.

The pivoted latches, indicated generally by the reference character I41, include a latch arm I48 and a magnet arm I48, all integral with one another. To condense the operating magnet aspossible alternate latches I41 have slightly diiferent configurations for their magnet arms so that the magnet arm I48 for the first latch I41, for instance, is substantially at right angles to the latch arm I48, while the magnet arm I48 (dotted lines, Fig. 11) for the second latch I4! is substantially parallel with the latch arm I48 therefor. The latch arms I48 for all of the latches are in alignment as shown in Fig. 11. All of the latches are pivotally supported upon a stationary shaft I5I, and are selectively pivoted into operating engagement with the control rings 33 by solenoids or magnets 83' mounted on the supplementary frame plate I29 and the bracket I3I as shown in Figs. 11 and 12. -A trigger I52 is pivotally supported on the end of each latch arm I48. The trigger comprises a plurality of radial portions which include a latch ear I53, for latching engagement with a switch gate I54, as will be described, and a stop ear I58 having a projection thereon for engaging the back edge of the latch arm I48. This engagement limits the pivotal movement of the trigger under the tension of the spring I51 connected intermediate a frame bracket I58 and a radial ear I58 of the trigger. A nose I8I comprises the remaining radial portion and this is of such a shape and size as to be complementary to the stopping tip of the latch arm I48 and increase the effective width of such tip.

The switching mechanism for the tuning unit includes a motor main line switch I82 and a reversing switch I88. These switches are mounted upon opposite sides of the frame plate I28 as shown in Figs. 11 and 12, with the switch I82 comprising a pair of contact members I84 and I88, and the switch I83 comprising a switch arm I8I with oppositely disposed yieldable contact members I88 and I88. Both switches are operated by the pivoted gate unit I54 which comprises a stamped-gout plate having a body portion extending intermediate the two switch assemblies as shown in Fig. 12. A transverse portion I12 carries a switch operating arm I13 with integral side extensions "I made of insulating material, and a flange I" over which the trigger ear I53 latches as shown in Figs. 11, 14,- and 15. An aperture I18 in the body portion of the gate is positioned so that an insulated stop plate I11 supported on the frame plate I28 may extend through the gate and rest in the back oi all of the latches I61, determining the limit of angular movement of the latches in a counter-clockwise direction under the influence of the springs H51. The stop plate ill is provided with shoulders H18 to define the back limit of pivoted counterclockwise direction by the switch gate H56 and hence the upward limit of contact 366 in the switch I62, and switch arm it? in the switch i823.

As is illustrated in Fig 11, in the idle position for the entire tuner mechanism the latches i431 are pulled upwardly, as viewed in Fig. 11, by the springs i51. By virtue of the beveled configuration of the nose of the trigger arm i153 which engages the flange 916, the trigger G52 is pivoted to snap into latching engagement with such flange on the gate. In the meantimethe switch contact I84 andthe switch arm I101 are holding the gate in retracted position, so that the switch operating mechanism is all latched together in an idle position, as willbe described more fully hereinafter,

A commercial adaptation of this modification of my invention is illustrated schematically in Fig. 17 showing a time control clock described in my copending application, Serial No. 239,696, filed November 9, 1938, including an arm 68! which is driven directly by a clock motor CM so as to complete an entire cycle of operation in twenty-four hours. A cam switch I82 is provided on the clock mechanism,.and this is designed to close every fifteen minutes in a twentyfour hour period. A plurality of conductors I88 are likewise provided on the clock mechanism and spaced so that the arm I8I engages .a conductor I83 once every fifteen minutes, thus extending a circuit from the particular conductor I83 through the movable contacts in the switch indicated generally by the reference character- I82. The conductors I83, in turn, are adapted to be interconnected with electric tuner leads by slidable contacts I84. A tuner lead as I88, in turn, is electrically connected with 9. corresponding latch magnet 88' on the tuner mechanism of the present invention. The circuit from the cam switch I82 extends through leads or conductors I81, I98, and 2M, to the negative terminal of a rectifier 282 which serves to energize all control circuits. The conductor I81 is likewise common to a plurality of push-buttons I88 which may be operated from a panel on the front of the radio receiver or from a unit remote from the radio receiver. An energizing circuit, as will be described, can be closed at fifteen minute intervals throughout a twenty-four hour period by means of the arm I8I and cam switch I82 as was described.

Simply from the standpoint of simplification of description, however, the operating circuit for the tuner will be described as originating through the closing of a push-button I88 which of course is in parallel connection to each other operating circuit through the clock mechanism. In the first place, the main line switch M, connected directly into the current supply line for the entire radio receiver system, is closed. With this closed. the power transformer I 8| is energized and current is available for operating a radio receiver aswell as the tuning mechanism. This also makes the operating circuit available for the timer motor II8. Closing a selected push-button switch I88 extends the circuit on one side through a conductor I82 to a corresponding latch magnet 88', and then to ground. On the other side 01' the push button the circuit is extended through conductor I88 to the negative side of the rectifier 282. The positive side of the rectifier is connected through lead 283 to magnet i823 and thence to ground. completing the circuit. Magnet 188 is thus in the common ground return circuit between all solenoids t8 and the rectifier Edd. Magnet i198 closes power relay i811 and energizes the heater and B supp circuits of the receiver whenever any solenoid 83 is operated.

Energizing the magnet ltd attracts the pivoted armature 2%, which in turn is secured to an insulating plate 285. When the armature 28 3 is in engagement with the core of the magnet ids a pivoted latching armature 2t? associated with the magnet 298 is pulled toward the right. as viewed in Fig. 17, by the spring 2% and latches the plate ZBSuncler the shoulders 288 on the armature i'ill. With the attraction of the armature 2% the contact unit 2 it on the plate 288 is brought into electrical engagement with corresponding contacts 21:; and did supported on an insulating plate 215 on the end of the relay frame, and a ground connection, is established through the contact 2 IE on the plate 2% and the conductor 2i? soldered or otherwise secured onto the metal frame for the power relay. The contact 2|8 is electrically connected with a third contact 2I8 on the plate 2I5. Contact unit 2I2, and its corresponding contacts 2I8 and 214 are in the output and filament circuits of power rectifier tube 220 completing the B supply circuit for the radio receiver when closed. Contact 2I6 closes the heater circuits for the receiving tubes utilizing secondary 2 I8 on the power transformer.

Although the motor voltage is available when the power transformer I8I is energized, it is not utilized until a push-button I88 is operated or an operating circuit is closed through the clock mechanism. The motor is connected, upon such closing, into a circuit including secondary winding I8I on the power transformer which is con nected on one side to ground and on the other through conductor I86 to motor switch I62. This circuit likewise provides the muting voltage via tube ,222 which supplies a rectified potential for muting the receiver during a tuning operation. The conductor 22! is connected to the switch arm I81, via a coupling condenser. Switch I88 serves to close the relay I81 and turn the set on manu- I62, energizing the motor. The contacts I61 and I88 remain closed with this action, and a corresponding field in the motor I I8 is energized to rotate the control assembly including the control ring 38' in a clockwise direction. This is shown in greater detail in Fig. 14. Rotating in a clockwise direction, the notch or recess R passes beneath the combined width of the nose I8I of the trigger and the tip of the latch arm I48. This width is greater than the width of the recess R and under the pivotal urging of the magnet 63' the latch arm ll8 merely drops to the low side L. This is the position shown in Fig. 15. -In this position the circuit through the switch arm I88 is opened, and that through I88 is closed thereby reversing the motor I18 and rotating the control assembly with the ring 38' in a counter-clockwise direction. This brings the nose I8I into engagement with the high shoulder of the recess R, pivoting the trigger I52, as shown in Fig. 16, the tip of the latch arm being pulled into a firm and complete engagement with the recess R by the magnet 53'.

When the trigger I52 pivots at the stopped position the latch ear I53 releases the gate I54 and the switch contact I, and arm I01 return the gate to idle position opening the motor circuit through the switch I62. This immediately deenergizes the motor I IS. The operating magnet 63' however, remains energized until the operator removes his finger from the push-button I09. With this operation the control assembly and hence the condenser H1 is always stopped at a predetermined tuning position while the control assembly is rotating in the same direction, namely a counter-clockwise direction for the embodiment of the invention as illustrated and described herein. This provides a positive and uniform stopping position for each of the control rings 39', and makes for greater precision and uniformity in the operation of the tuning mechanism and hence the tuning of the radio receiver. The power relay armature 204 may be opened by closing the "off switch 228 which is connected to a conductor 229, connected in turn to the magnet or solenoid 208 of the power relay. When this magnet is energized it attracts the pivoted armature 201 releasing the plate 206 from the shoulders 2 of such armature and permitting such plate to be pivoted away from the contacts 2l3, 2H and 2l0 by the spring 23L The magnet 208 is in the circuit with the rectifier 202 by means of a conductor 232 which in turn is connected to the conductor 203 extending to the rectifier 202. The

other side of the rectifier 202 is connected by conductors 2M and I! to push button 220, completing the circuit.

Although I have illustrated and described my invention in its preferred embodiments, it is to be understood that modifications and alterations therein may be made which are within the full intended spirit and scope of my invention as defined by the appended claims.

I claim:

1. Radio tuning apparatus having frequency changing means and rotary control means operatively connected with said frequency changing means, said rotary control means including a plurality of coaxially mounted control rings each having a stop recess in the peripheral edge thereof, a plurality of pivoted latches corresponding to said rings, with each of said latches having a stop portion thereon engageable with a corresponding recess to stop said control means at a predetermined control position, means for setting each of said control rings to a predetermined control position including a corresponding latch, an armature portion operatively connected to each of said latches, an operating magnet for each of said latches arranged to attract a corresponding armature to pivotally move a corresponding latch into engagement with a corresponding con trol ring, means individual to each latch for moving the same out of engagement with a corresponding control ring after its rotation to a predetermined control position, motor drive means for said rotary control means, and means for selectively actuating said magnets to individually operate said latches.

2. Electrical tuning apparatus for a radio receiver having frequency changing means, rotary control means for moving said frequency changing means to predetermined tuning positions, said control means including a plurality of coaxially mounted control rings having a stop recess in the peripheral edge thereof, a plurality of pivoted latches corresponding to said control rings, with each latch having a stop portion thereon engageable with a corresponding recess, magnet means for each of said latches arranged to pivotally operate a corresponding latch into engagement with a corresponding control ring, a motor for driving said rotary control means, a circuit for said motor and magnet means, means for selectively energizing said circuit to substantially concurrently operate a selected latch and rotate said control means, with engagement of said latch stop portion in a corresponding recess stopping rotation of said control means at one of said predetermined tuning positions, means individual to each latch for moving the same out of an engaging position with the corresponding control ring on deenergization of a corresponding magnet means, and means for setting each of said control rings to a predetermined control position in cluding a corresponding latch.

3. In an electrical tuning device for a radio receiver having frequency changing means, rotary control means operatively connected with said frequency changing means for moving said frequency changing means to a predetermined tuning position, said rotary control means including a control ring having a stop portion in the edge thereof, a pivoted latch for said control ring, magnet means operatively associated with.

said latch and arranged to pivotally move the latch into engagement with said ring, spring means engageable with said latch for returning it to a rest position immediately after the operation of said magnet means, a motor for driving said rotary control means, with engagement of said stop portion and latch defining said predetermined tuning position of said frequency changing means and stopping the rotation of said control means, and means including said latch for setting said control ring to a predetermined control position.

4. A preassembled electrically operated radio tuning unit including a frame having a mounting wall thereon, a variable condenser mounted on one side of said wall and rotary control means on the other side of said wall operatively connected with said variable condenser, said rotary control means including a plurality of coaxially mounted'rings each having a stop recess in the edge thereof, a plurality of coaxially mounted pivoted latches corresponding in number to said rings, with each latch having a stop portion at one end and an armature portion at the other end, means for setting each of said control rings to a predetermined control position including a corresponding latch, an operating magnet for each of said latches adapted to be selectively and individually energized to pivot a corresponding latch into engagement with a corresponding control ring, means individual to each latch for moving the same to a rest. position after deenergization of a corresponding operating magnet, motor drive means for said rotary control means, and a switch mechanically common to all of said latches operated upon pivotal movement of a selected latch to energize said motor and rotate said control means to a position at which the stop portion of the selected latch is in alignment with the recess in the corresponding ring, with the energized magnet attracting the armature portion thereto and acting to pivot the stop portion or the latch into stoppin engagement with said recess.

5.1n a radio tunerhavingaframaarotary member with a plurality of adjustable stops thereon mounted on said frame, and an electric motor for driving said rotary member, means for changing the direction of rotation of the motor and stopping said rotary member at predetermined stop positions, said means including a plurality of pivoted latches, each latch having a stop portion on one side oi. the pivotal axis therefor and with all of said stop portions being substantially identical in configuration, and having an armsture and arm portion on the other side of the pivotal axis with some of said armature and arm portions being of one configuration and other of said armature and arm portions being of another configuration, an energizable magnet for each of said latches, with some of said magnets being mounted in one position on the tuner frame and other of said magnets being mounted in another position on the timer frame to conform to the diiferent configurations of the armature and arm portions of said latches.

6. In a tuning device for a radio receiver having a frequency changing means and rotary control means for moving said frequency-changing means to a plurality of predetermined tuning positions, said control means including a plurality of coaxially mounted control rings having oppositely extending circumferential portions of different radial heights and a recess intermediate the same, a plurality of pivoted latches corresponding to said control rings, each of said latches having a plurality of radially extending arms, one of said arms having a stop portion thereon adapted for seating engagement in a corresponding one of said recesses to define a predetermined tuning position of said frequency changing'means, magnet means operatively connected with a second arm on each of said latches and arranged to pivotally move a corresponding latch into engagement with a corresponding control ring, a reversible motor drive for rotating said control means, a reversing switch for said motor mechanically common to all of said latches and in engagement with a third arm on each thereof, engagement of said one arm with one of said circumferential portions positioning said reversing switch to efiect a rotation of said motor in one direction, and its engagement with the other of said circumferential portions positioning said switch to effect a rotation of said motor in an opposite direction.

7. A radio tuning device having irequency changing means, rotary control means for moving said frequency changing means to a predetermined'tuning position, said control means including a control ring having two circumferential portions of diiierent radial heights with a recess therebetween, a. pivoted latch having a stop ortion thereon for seating in said recess. magnet means operatively associated with said latch and arranged to pivotally move the latch into engagement with said ring, spring means for returning said latch to its rest podtion, a reversible motor for driving said rota y control -means, a reversing switch for said motor arranged for actuation by said latch to two operating positions, one of said positions being in correspondence with an engaged position of said latch with the circumferential portion of lesser radial height, the engagement of said stop portion in said recess defining the predetermined tuning position of said condenser and stopping the rotation of said control means. with said latch being in engagement with said portion of lesser radial height immediately prior to a stop- DinI- of said rotary control means, and a circuit for said magnet means and motor arranged to substantially simultaneously energize said magnet means and motor on a closing thereof.

8. In combination with a radio tuning device having an electriccontrol switch thereon, a rotary member having a pair of oppositely extending circumferential control surfaces of diflerent radial heights and a stop recess intermediate the same, means for causing the rotation of said rotary member and also stopping the same,ineluding a pivoted latch having a plurality of substantially radially extending integral portions, with one 01 said portions having an armature thereon, a second of said portions including a stop tip for engagement with one circumferential control surface or the other and adapted to engage said stop recess, a third of said portions having. a pivoting limiting ear, and with a fourth portion including an ear for direct engagement with the electric control switch to-opcrate the same and vary the direction of rotation of the rotary member.

9. In radio tuning apparatus including an elec trio driving motor and a rotary control member driven thereby having a pair of engageablc surand an armature portion at the other end with the pivotal axis intermediate said ends, a magnet adapted to be energized to attract the armature portion of the latch and pivot the stop tip into engagement with the control member, and switch means having a pair of contact portions and a closing member, with one of said contact portions in electrical connection with said magnet and positioned in said switch means so as to be engaged first on the operating movement of said closing member to energize said magnet, and the other of said contact portions in electrical connection with said motor and positioned in said switch means so as to be engaged by said closing member subsequent to its engagement with the first contact portion, with said subsequent engagement acting to energize said motor and with the first engagement being maintained while maintaining the subsequent engagement, whereby said motor drives said control member to an angular position at which the latch is pivoted by said magnet to project the stop tip into the control member recess to stop the control member.

10. An electrical tuning device for a radio receiver having a variable condenser, rotary control means operatively connected with said variable condenser, a plurality of control rings coaxially mounted on said rotary control means, each ring having oppositely extending circumferential portions of diiierent radial heights and 

